Knife grinding



Nov. 23 1926. I 1,608,140

' T. c. SHEEHAN KNIFE GRINDING Filed Dec. 1924 BY Y Wage ' ATTORNEY Patented Nbv. 2a, 1926.

UNITED STATES PATENT OFFICE.

THOMAS C. SHEEHAN, OF UPPER MONTCLAIR, NEW JERSEY, ASSIGNOR TO WADE & BUTCHER CORPORATION, A CORPORATION OF NEW JERSEY.

KNIFE GRINDING.

Application filed December 6, 1924. Serial No. 754,418.

This invention relates to an improvement heretofore been'considered more or less satisfactory in accordance with the degree of' finish desired. 'VVhen a mirror-like, surface has been desired, it has heretofore been necessary to supplement the grinding operation by 'a. tedious and expensive polishing operation, usually manually performed, which greatly increased the cost of the article. It has now been discovered that certain abradants possess properties which may be utilized in the grinding of table knives and" other articles by means of a new method and apparatus, the use of which results in the production of articles having a mirror-like finish at an extremely low cost, even-below that of similar articles heretofore produced which lacked a mirror-like finish. Emery, for example, although its specific gravity is greater than that of water, when reducedto a powder, becomes what may be termed a flotative abradant; that is to say, the powdered emery will float or .will remain in suspension in still water for aperiod which depends upon its degree of fineness. In fact, the degree of fineness of powdered emery, which cannot be measured by the ordinary screening method used for coarser emery, may be, and is, measured by the period during which it will remain flotative or in suspension in still water; and the period during which the abradant retains its flotative property maybe extended indefi the water to keep the nately by agitating flotative abradant'i nmotion in the water while any larger particles that may be pres;

-ent will sinkand accumulate in the bottom of the pool of water.

Althoughthis flotative propertyof abra- I dant has long been known, the only 'use, of

tained by the use of grinding wheels have which I am aware, to which it has been put, is n the grading of the finer abradant powders, as above indicated. The main object of the present invention 1s. the production of a grinding method and apparatus wherein this flotative property of abradants is utilized to obtain superior results at a greatly reduced cost. Another obect of the invention is the production of a. machine in which such a method is employed, and which operates automatically and without the employment of skilled labor, to still further reduce the cost of producing the articles ground. With these and other objects not specifically mentioned in view, the invention resides in certain methods, apparatus and machines which will be herein after fully described and then specifically set forth in the claims hereunto appended.

. In the accompanying drawings, which form a part of this specification and in which like characters of reference indicate the same or like parts, Fig. 1 is a side elevation, partly in section, of a machine constructed-in ac cordance with the invention; Fig. 2 is a detail front elevation of a part of the structure shownin-Fig. 1, the part being indicated by the broken line 2-2 in Fig. 1; Fig. 3 is a cross-sectional view taken on the line 33 in Fig. 2, and Fig. 4 is a detail plan view taken on the line 4-4 in Fig. 1,

the grinding member being indicated in dotted lines.

v In carrying the'invention into effect, there isprovided a method of, and apparatus for, grinding a surface by producing a relative rubbing movement of said surface and of a relatively soft and inherently non-abrasive member, and simultaneously causing .a liquid carrying a relatively small quantity of. flotative abradant to pass between said surface and said member. In the best practice of the invention, therubbing movement of the surface to be groundand of: the operating surface of the relatively soft and inherently non-abrasive coacting member occursjwhile the two surfaces are subme'rgedin the liquid carryingthe relatively small quantity of flotative abradant, and the abradant is caused to pass between the two surfaces by the flow' of the; liquid which is produced by the relative movement of the surfaces. In the best practice of the invention also,

thegrinding'is effected in threestages, the

relative movement of the surface to be ground and of the coacting member being different in each stage, in order to'entirely eliminate all traces of marks made by the abradant on the surface of the article in operation, so that the surfaces will have a mirror-like finish. In the best practice of the invention also, the pressure of the member against the surface to be ground differs in the three grinding stages. For the initial stage, a mean effective pressure of 150 lbs. has been found to give the best results; while at the third stage, a mean effective pressure of only 2 lbs. has been found to give the best results. For grinding some articles which do not require a high finish, the first stage of the present method is sufficient to accomplish the end sought; for

grinding articles of another'class which require a better finish than the articles just mentioned, though not a mirror-like finish, the first two stages of the present method are necessary to accomplish the end sought;

- all three stages, however, are necessary to the production of such articles as table .knives having a mirror-like finish entirely free from any trace of abradant marks.

All the apparatus that is essential to practice of the invention in its simplest form is a member ofwood, or other inherently nonabrasive material, having an operating surface adapted to contact with the surface to be ground, and some means for causing a liquid carrying ,a relatively small quantity of fiotative abradant to pass between the surfaces; and the necessary rubbing movement may be manually produced. The abradant carrying liquid may be confined in a pool and caused to pass between said surfaces by means of the relative rubbingmovement of the two surfaces. While the end sought can be accomplished by such manual practice of the invention, it is not the best way because it is not the most economical. When used for knife grinding, one operator could grind only one blade at a time. By the use of the machine to be hereinafter described, however, one operator can grind 40 blades while the manual operator is grinding one. I J

Referring to the drawings, which illus trate a machine-r rather one unit of a.

multiple unit machineconstructed in accordance with the invention, 5 indicates the upper part of a pedestal carrying a bracketv 6 at its side and a bed plate 7 at its top. Stationarily mountedin uprights 8 on the bracket 6 are two rollers 9-,9, and resting upon these rollers is a carriage 10 surmounted by a support 12 for a 001 13 of liquid carrying a relatively smal quantity of flotative abradant and for a knife blade k'b submerged in said liquid. This pool is confined in'a pan 14: formed. integrally with the support-12. The pan 14 has an sive material. Birch-wood hasbeen found to be peculiarly adapted for present purposes, although other non-abrasive material which is softer than the steel of the knife blade may be used. The member 17 is secured to a disk 18, screwed on a spindle 19 which is journaled in bearings 2020 formed on a bracket 21. The bracket 21 is secured to the side of the upper bed plate 7 before referred to. The upper end of the spindle 19 terminates in a flanged cup 22, and a helical spring 23 bears against the flange of the cup 22 and against a ball thrust bearing 24, which in turn bears against a collar 25 pinned to the spindle 19.

The cup 22 is centered in alignment with the axis of the spindle 19 by means of an adjustable centering screw 26 carried in the upper part 27 of the bed plate 7 before referred to. It will be understood that the tendency of the spring 23 is to move the spindle 19 and member 17 downwardly to cause the latter to bear under pressure on the knife blade 7cb.

Splined to the spindle 19 is a pulley 28, and overrunning this pulley is a belt 29 whichalso overruns a driving pulley 30, fast on a shaft 31., joiu-naled in a bearing 32, carried by the bed plate 7. The shaft 31 carries a bevel gear 33 in mesh with and driven by a bevel gear 34, the latter being fast on a shaft 35 which is the main power shaft of the machine and is journaled in bearings in the bed plate 7.

The" power shaft also carries a pulley 36 over which runs a belt 37 overrimning and driving a pulley 38 which is fast on a short shaft 39 journaled in the side of the pedestal 5. The shaft 39 carries a crank 40 which is connected to a link 41 which is .also connected to the carriage 10 before referred to.

By the mechanism so far described, the member 17 is rotated at a given speed, and the support 12 is reciprocated at a slower speed, the mechanism. for producing these movements being interconnected. As the member 17 rotates, fine particles of abradant which are carried in suspension in the pool 13 are carried in between the operating surface of said member and the upper surface of. the knife blade 7cb, the pool being agi-,

tated by the centrifugal force exerted by the whirling member .17. Simultaneously, the support 12, and of course the pool 13, and the knife blade, are given a relatively termediate parts.

-ly embedded J therein.

slow reciprocating movement, so that the grinding effect is progressive along the knife blade.

Mechanism is provided for disengaging the member 17 from the knife blade 70-4), while the direction 'of support reciprocation is changed at one end of the travel of the carriage 10 where the knife blade is thinnest,

to avoid excessive grinding at this point when the blade is temporarily stationary. This mechanism includes a cam block 42, fast on the block 11 before referred to, and therefore moving with it. It further includes a bell-crank 43-44, fulcrumed at to the under side of the bed plate 7. The arm 43 of this bell-crank carried a roller 46, tracking on the top of the block 11 and coming into engagement with, and being lifted by, the cam 42 atone end of the support reciprocation. As the bell-crank 43-44 is operated by the cam 42, its arm 44 engages the under side of, and lifts, a plunger 47 slidable in the bracket 21 before referred to. The upward movement of this plunger raises a screw 48 which has a pin and slot connection with a lever 49, fulcrumed at 50 to the bracket 21, and'having a pin 51 engaging a collar 52 on the spindle 19. Thus, the upward movement of the screw 48 lifts the spindle 19, which in turn lifts the member-17 and disengages it from the knife blade and. holds it in disengaged relation therewith until the roller 46 leaves the cam' 42.

Means are provided for automatically adjusting the member 17 as it wears away. This means includes the lifting mechanism just described, and another device. The screw 48 is provided with a ratchet head 53, engaged by a pawl 54, formed on a bell-crank 5556, which is fulcrumed at 57, to the bracket 21. The arm 56 of the bell-crank 5556 engages the lower end of the screw 48. When the spring 23 forces thespindle 19 downwardly as the member 17 slowly wears away, the lever 49 is forced-down with it; and this lever, through the action of its pin and slot connection at 58 with the screw 48, forces the latter downwardly, the-screw not being threaded in the bearings of the bracket2l in which it is mounted. As the. descending screw 48 presses against the short arm 56 of the bell-crank 55-56, the long arm 55, carrying the pawl 54, is given a movement which operates the ratchet 53v and turns the screw 48. This action automatically readjusts the normal relative positions of the bell-crank 43-44, the lever 49,'and the ini As the li uid carrying the flotative abradant passes etween theknife blade and the member17, the-fine particles of abradant are 1 forced into the relatively .soft material of saidmember until they are almost complete S0 embedded, the. move across the surface of the blade, yield:

ingly and therefore gently and slightly wearing away the steel 1n their respective paths. But whenthey have passed the blade, they are washed by the agitated liquid out .of the beds they hadmade for themselves in said member; and when they again reach. a position between the blade and member, they become embedded in said member in new positions. Thus, the particles of abradant do. not w accumulate on the operating surface of the member,'but constantly change their positions, constantly presenting new patterns of particles to the blade and thereby avoiding the formation of the grooves and ridges in the blade surface which are inevitably produced by the same abradant when used in the commercial solid wheel form.

The only duty the'operator of the machine has to perform is to place a knife blade in positionvon the magnetic chuck ldbefore it is ground,"-and'take it off when the grinding operation is finished, No skilled labor, therefore, is required the operation of the machine.

The time required for the grinding operation, and the time required for the-substitution of an unground knife blade for a ground knife blade in the machine, are such that one operator can keep in operation approximately 40 spindles, so that 40 blades will be undergoing the grinding operation at the sametime; and by placing blades successively on the 40 chucks, the machine can be kept in operation continuously. Although the drawings show but one spindle, the commercial machine may have any number up to a maximum which is controlled by the rapidity with which an operator can substitute unground blades for ground blades; and the several units will all be alike.

It will be recalled that in the machine shown and; described, the relative rubbing movement of the blade and of the relatively soft and inherently non-abrasive member. which coacts therewith, is the resultant of a rotating movement of the member and a reciprocating movement ofthe blade, the former being rapid and the latter being slow.

While, as hereinbefore noted, the single stage operation is sufficient for some purposes, on the ground surface. When, therefore, a higher degree of finish is desired and the second stageoperat-ion is ractieed, it is done it does leave visible abradant marks by-means of a machine 1' e that used inthe first stage operation excepting that the member 17 is rotated at a lower speed than before, while the blade isreciprocated at a higher speed than before. Obviously, this result may be accomplished by changing the pulleys on 'the samemachine, or by using other machines, otherwise like the present machine but having a different drive ratio. The different relative movement; produced:

'lar machines being used witha third relative movement of blade and coacting member, with a felt member in place of the wood member used in the first two stage operations, with a finer abradant than the emery used in the first two stage operations, and with greatly reduced pressure. In the third stage operation, the rotating member has a." higher speed than 1n either of the first two stage operations, while the blade is reciprocated at a slower speed than in either of the first twostage operations.

It has been found that the best results are obtained, when a mirror-like finish is desired, by using the commercial product known as 4 F emery as the flotative abra-c dant in the first two stage operations; and by using the commercial product known as Chromotron as the flotative abradant in the third stage operation; 1

Changes and variations may be made in the methods, apparatus, and machines, by means of Which the invention is carried into effect. The inventiomtherefore, is not to be restricted to the PIBCISBJ details of the ma-' chine shown and described.

What is claimed is: v

1. The method of, and apparatus for, grinding, as herein described, by causing particles of flotativeabradant to be repeat edly embedded in ever-varying patterns in, and washed out of, a soft non-abrasive medium movably contacting witha surface to be ground.

2. The method of grinding, which. consists in forming a pool of liquid containing v a modicum of flotative abradant, then submerging in said pool asurface to be ground and a relatively soft non-abrasive medium contacting with said surface, then producing a relative movement of said surface and said medium to keep said l quid in motion and to cause particles of said abradant tobe repeatedly caught in ever-varying patterns between said surfaceand said medlum and embedded in said medium and alternately Washed out of said medium.

, 3. The method of grinding, which consists in forming a pool of liquid containing a modicum of flotative abradant, then submergingin said pool a'surface to be ground and a relatively soft non-abrasive medium contacting with said surface under pressure whichiis predetermined in accordance with the nature of the finish desired, .then producing a relative movement of said surface and said medium to keep said liquid in motion and to cause particles of said abradant to be repeatedly caught in ever-varying patterns between said surface and said medium and embedded in said medium and alternately washed out of said medium.

4. The method of grinding, which consists in forming a pool of liquid containing a modicum of flotative abradant, then submerging insaid pool a surface to be ground and a relatively soft non-abrasive medium contacting with said surface, then producmg a relative movement of said surface and. said medium which is the resultant of areciprocating movement of said surface and a rotating movement of said medium to keep said liquid in motion and to cause particles of said abradant to-be repeatedly caught in ever-varying patterns between said surface and said medium and embedded in said medium and alternately washed out of said- Inedium.

5. The method of-grinding, which consists in forming a pool of water containing a modicum of flotative abradant of a fineness approximating that of chromotron, then submerging in said pool a surface to be ground and a relatively soft nonabrasive medium contacting with ,said surface, then producing a relative movement of said surface and said medium to keep said water in motion and to cause particles of said abradant to be repeatedly caught in ever-varying patterns between said surface and said medium and embedded in said medium and alternately washed out of said medium.

6. Means for grinding, comprising means for supporting a pool of liquid containing a modicum of flotative abradant, means for supporting an article with a surface to be ground submerged in said pool, a nonabrasive medium which issofter than and contacts With said surface, and means for producing a relative movement of said surface and said medium to keep said liquid in motion and to cause particles of said abradant to be repeatedly caught in evervarying patterns between said surface and said medium and embedded in said medium and alternately washed out of said medium.

7. Means'for grinding, comprising means for supporting a pool of liquid containing a modicum 'of flotative abradant, means for supporting an article with a surface to be ground submerged in said pool, a non-abrasive medium which is softer than and confacts with said surface, means for pressing said medium against said surface with a pressure which is predetermined in accordance with the nature of the finish desired, and means for producing a relatiye movement of said surface and said; medium to keep said liquid'in motion and to cause particles of said abradant to .b e repeatedly caught in ever-varying patterns between said surface and said medium and embedded in said medium and alternately washed out of said medium.

modicum of fiotative abradant, means for supporting an article with a surface to be ground submerged in said pool, a nonabrasive medium which is softer than and contacts with said surface, and means for producing a relative movement of said surface and said medium which is the resultant of a reciprocating movement of said surface and a rotating movement of said medium to keep said liquid in motion and to cause particles of said abradant to be repeatedly caught in ever-varying patterns between said surface and said medium and embedded in said medium and alternately washed out of said medium.

9. Means for grinding comprising means for supporting a pool of liquid containing a modicum of fiotative abradant, means for supporting an article with a surface to be ground submerged in said pool, a nonabrasive medium which is softer than and contacts with said surface, and means for producing a relative movement of said surface and said medium which is the resultant of a reciprocating movement of said surface and a relatively rapid rotating movement of said. medium to keep said liquid in motion and to cause particles of said ab repeatedly caught in ever-varying patterns between said surface and said medium and embedded in said medium andalternately washed out of said medium.

In testimony whereof, I have signed my name to this specification.

THOMAS C. SHEEHAN.

'adant to be 

